Microplastics in Soil: Inventories, Effect and Environmental Risks

Abstract The omnipresence of microplastics (MPs) in the environment has garnered immense scientific and public interest. Recent studies indicate that these contaminants are not restricted to the aquatic environment but probably are more prevalent in terrestrial systems, including agricultural soils. Soils are vulnerable to MP contamination through multiple pathways, including the disintegration of plastic mulches, sewage sludge for soil amendment, irrigation with wastewater, and atmospheric deposition. We present a comprehensive synthesis of the current literature on microplastics in soil systems, focusing on their occurrence, impacts on soil properties, including microbial assemblages, and potential to affect biogeochemical cycling. A systematic literature search was conducted using major scientific databases, and over 150 articles published between 2010 and 2024—including review papers from leading Elsevier and Springer journals—were evaluated. The findings reveal that microplastics can alter soil physical and chemical properties and affect the rhizosphere’s nutrient cycling and microbiota. It also shows the lack of standardisation among the methodologies and often lack quality control in reported data. The current research provides insights into microplastic-soil interaction, but significant gaps remain regarding the long-term implications of microplastic accumulation in soils. Future studies should address standardised detection methods, elucidate crop uptake mechanisms, and assess the impact on food safety and human health. The chapter underscores the urgent need for harmonising methodologies and undertaking simulation modelling to understand the long-term effects of microplastics in soil and to design policies to mitigate MP contamination in soil systems.